It is desirable to be able to monitor items or containers during shipment. One known technique for tracking items or containers is to mount a radio frequency identification (RFID) tag on each item or container to be tracked. These RFID tags can transmit wireless signals, and some tags can also receive wireless signals. Where the object being tracked is a container, there are situations in which it is desirable to be able to monitor one or more environmental conditions within the container, such as the temperature and/or humidity.